1. Technical Field
The present invention relates generally to apparatuses for testing torque of assemblies such as lens modules; and particularly to a fixture for fixing a torque meter, and an apparatus having the fixture and a torque meter for testing torque.
2. Discussion of Related Art
With the ongoing development of optical imaging technology, lens modules are now widely used in a variety of electronic devices, such as digital cameras and mobile phones.
A lens module generally includes a barrel holder, a barrel threadedly engaged with the barrel holder, and a number of optical members (i.e., optical lenses, filters, and spacers) received in the barrel. During assembling of the lens module, the optical members are firstly disposed in the barrel, and then the barrel is screwed into the barrel holder. To screw the barrel, a torque must be applied to the barrel. Once the screwing process is completed, the barrel is held in its final position by friction between the barrel and the barrel holder. However, friction (rubbing) occurring between the barrel and the barrel holder during the screwing process may cause either or both of the barrel and the barrel holder to deform.
To ensure that the performance of a lens module satisfies its design requirements, the amount of friction must be limited within a predetermined range. When the amount of friction is limited within the predetermined range, any deformation of the barrel and the barrel holder is considered to correspondingly be within acceptable limits. Thus after the screwing process, the friction between the barrel and the barrel holder should be tested using a torque meter. The torque meter shows how much force must be applied to displace the barrel from its final position and completely unscrew the barrel from the barrel holder. Thereby, the torque meter shows the amount of friction between the barrel and the barrel holder. This testing process is generally called torque testing.
During typical torque testing of the lens module, firstly, a platform is provided for supporting and fixing the barrel holder of the lens module; secondly, a fixing end of the torque meter is fixed on the barrel; thirdly, a testing end of the torque meter is rotated until the barrel is unscrewed out of the barrel holder. A maximum torque recorded by the torque meter is the maximum amount of friction between the barrel and the barrel holder.
However, nowadays, many lens modules are becoming smaller and smaller in size with each new product release. It is difficult to fix a torque meter on a small-sized lens module. Additionally, it is difficult to ensure that a central axis of the torque meter and an optical axis of the lens module coincide with each other throughout the torque testing process. As such, the torque meter may provide imprecise testing results.
Therefore, what is needed is to provide an apparatus or means which is capable of overcoming the aforementioned problems.